Method for signaling an incoming call

ABSTRACT

According to the inventive method, an incoming call that is directed to a subscriber terminal (Tln 1 ) allocated to a subscriber group (Tln 1  to Tln n) is signaled to the subscriber terminal (Tln 1 ) called and additionally to at least one subscriber terminal (Tln A 3  to Tln An) that is located outside the signaling transmission range of the subscriber terminal called.

[0001] The invention relates to a method for signaling an incoming call,which is directed to a subscriber terminal which is associated with asubscriber group and which a subscriber can also accept on any othersubscriber terminal associated with that subscriber group instead of onthe subscriber terminal being called, as claimed in theprecharacterizing clause of patent claim 1.

[0002] Subscriber groups such as these are related, for example, withthe feature “Centrex” (Central Office and Exchange). The Centrex featureallows subscriber terminals which are connected to a common telephoneexchange, or are each connected to different telephone exchanges, in atelecommunications network via subscriber access lines to be combined toform a Centrex group. The subscribers who belong to the Centrex groupmay then be provided by the telephone exchange which is responsible forthem with virtually the same service features which a private branchexchange (PBX) would offer them if their subscriber terminals wereconnected to it.

[0003] Typical service features which are provided to the Centrexsubscribers, and some of which correspond to a private branch exchange,are, for example:

[0004] access to the telecommunications network by means of an accesscode,

[0005] special charge handling for Centrex-internal connections,

[0006] exchange authorizations for incoming and outgoing calls,

[0007] call transfer,

[0008] call pick up,

[0009] service features relating to a call center (attendant features),

[0010] secretary and team functions,

[0011] various audible signals (“ringing” etc.).

[0012] In order to make it possible to provide the call pick up servicefeature which has been mentioned, a so-called call pick up group isformed within a Centrex group. A subscriber who belongs to a Centrexgroup may in this case be associated with a number of different callpick up groups.

[0013] The call pick up service feature and further service featureswhich are related to the Centrex groups are described, by way ofexample, on pages 42 and 43 of a customer brochure “GeoCentrex: The BestCatch for your Network” from Siemens AG, issued in 1995 byGeschäftsgebiet Telekommunikationsnetze, Hofmannstr. 51, D-81359,Munich, Order No. A 308080-X3093-X100-1-7635. This brochure describesthree types of call pick up service feature, namely call pick up withina group, directed call pick up and call pick up in conjunction with anight-time service, with the call pick up within a group service featurein practice being that which is most frequently used. According to this,Centrex subscribers are combined to form a Centrex call pick up group.This allows a subscriber who is associated with a call pick up groupalso to accept an incoming call which is directed to a subscriberterminal associated with that call pick up group at any other subscriberterminal which is associated with that call pick up group rather than onthe called subscriber terminal. To do this, the subscriber dials aso-called call pick up access code on the subscriber terminal on whichhe wishes to take the call. There may also be a number of different callpick up groups within one Centrex group. In a situation where a numberof incoming calls occur at the same time within a call pick up group andone subscriber wishes to take a call on another subscriber terminal inthe described manner, the call which has already been waiting for thelongest time is passed to this subscriber.

[0014] Operation of the known call pick up service feature is dependenton each subscriber terminal which is associated with the call pick upgroup, as well as the subscriber, being located within a physical areawhich allows a call which is directed to a subscriber terminal which isassociated with that call pick up group to be perceived audibly orvisually by the subscribers. If the subscribers in a call pick up groupare not located in an area such as this, that is to say within audibleor visual range, for example because their workstations are accommodatedin physically separate offices, then the subscribers cannot audibly orvisually perceive an incoming call which is directed to a subscriberterminal which is located in a different office or room, and can thusnot pick up the call in the described manner.

[0015] This disadvantage is particularly apparent when a call pick upgroup is set up throughout the network for subscribers whose subscriberterminals are connected to different exchanges. This is because thesubscribers in a call pick up group whose subscriber terminals areconnected to different exchanges are generally located in a physicallyseparate area. An unfavorable situation such as this also occurs whenmobile subscriber terminals in a mobile radio network are associatedwith such a call pick up group. The mobile terminals are generally notlocated within audible range of the other call pick up group members.The handling of Centrex service features with regard to subscribers to amobile radio network and to a landline network has already been proposedin German Patent Application 198 52 774.8.

[0016] The object of the invention is to improve a method for signalingan incoming call in the manner specified in the precharacterizing clauseof patent claim 1.

[0017] This object is achieved by the features specified in thecharacterizing part of claim 1. Advantageous refinements of theinvention are characterized in dependent claims.

[0018] The major aspect of the method according to the invention is thatthe incoming call is signaled not only to the called subscriber terminalbut also to at least one subscriber terminal which is located beyond thesignaling range of the called subscriber terminal.

[0019] The expression signaling range of a subscriber terminal should beunderstood as meaning the range of a call signal within whichsubscribers can perceive, for example audibly or visually, an incomingcall. The subscriber terminal to which the incoming call is additionallysignaled may also be connected to an exchange other than that of thecalled subscriber terminal. Furthermore, one subscriber terminal may beassociated with a number of such subscriber groups.

[0020] The advantage of the method according to the invention is, inparticular, that the call pick up service feature can, in particular, beextended to subscribers whose subscriber terminals are each locatedbeyond the signaling range, for example in separate rooms, or whosesubscriber terminals are each connected to different exchanges in thetelecommunications network. The call pick up service feature thus alsooperates beyond network boundaries. For example, a subscriber terminalin the subscriber group can be connected via a landline networkconnection to a switching center, and a further subscriber terminal maybe a mobile terminal, which is normally connected via an air interfaceto a base station which is connected to a mobile switching center in amobile network (for example GSM or UMTS) which is connected to saidlandline network.

[0021] The procedure according to the invention also allows said callpick up service feature to be extended to subscribers who use atelephone service via a packet switching data network (for example viavoice over IP) which is connected to the landline network. According tothis, an incoming call which is directed to a subscriber terminal whichis associated with a subscriber group could also be signaled tosubscriber terminals which belong to the subscriber group and can beaccessed via such a data network. Conversely, incoming calls which aredirected to such subscriber terminals which can be accessed via such adata network can also be signaled to subscriber terminals, which areassociated with that subscriber group, on a landline network.

[0022] Furthermore, the additional signaling to the subscriber terminalwhich is located beyond the signaling range of the called subscriberterminal can be carried out in parallel or with a time delay withrespect to the signaling of the incoming call to the called subscriberterminal.

[0023] In addition, the at least one subscriber terminal which islocated beyond the signaling range of the called subscriber terminal canbe defined in advance for receiving the additional signaling within thesubscriber group, thus making it possible to shorten the delay time forthe signaling process.

[0024] One development of the invention provides for the capability fora subscriber terminal which is associated with the subscriber group butis located beyond the signaling range of the called subscriber terminalto be associated with subgroups. Within a subgroup such as this, onesubscriber terminal is defined for receiving the additional signaling.This makes it possible to define specific target groups within thesubscriber group, for example people in a secretarial office or in adevelopment laboratory, for receiving the additional signaling.

[0025] The subgroups are expediently formed such that the subscriberterminals which are associated with such a subgroup are located withinthe signaling range of the at least one subscriber terminal to which theincoming call is additionally signaled.

[0026] According to one advantageous refinement of the invention, one ormore subscriber groups are defined by the contents of a table which isstored in a switching center in a telecommunications network. Theprocedure according to the invention for defining in advance asubscriber terminal in the subscriber group for receiving the additionalsignaling within the subscriber group can be carried out more easily byamending the table contents.

[0027] One development of the invention provides specific table fieldswithin the table for definition of an individual subscriber group. Thedefinition of the subscriber groups or, expressed in other words, theassociation of a subscriber terminal with a subscriber group, is in thiscase carried out by entering its call number in these table fields whichare provided for that subscriber group. This ensures a level of claritywhich is used in particular in conjunction with the maintenance andadministration of this table.

[0028] A further advantageous refinement of the invention provides forthe one or more subscriber terminals to which the incoming call isadditionally intended to be signaled to be defined by the contents of afurther table. This further table is linked to the table which definesthe subscriber group, and is likewise stored in the same switchingcenter. This ensures that the association of a subscriber terminal witha subscriber group, as well as the at least one subscriber terminal towhich the incoming call is additionally intended to be signaled, can beadministered independently of one another. Data consistency between thetwo tables is ensured by linking them.

[0029] The table which defines the subscriber group and the furthertable which is linked to it are expediently stored in a central databasein the switching center. This ensures consistent and rapid data accessto said tables.

[0030] It is sensible for said further table to contain at least thecall number of the at least one subscriber terminal to which theincoming call is additionally intended to be signaled. Further callnumbers can be entered in this table by subscriber terminals associatedwith that subscriber group.

[0031] Subgroups of the type mentioned above relating to a subscribergroup may be formed, if required, by grouping these call numbers whichare entered in said further table. Within such a subgroup, at least onecall number may then be identified as a special call number to whosesubscriber terminal the incoming call is additionally intended to besignaled. Groupings such as this allow subscriber terminals in thesubscriber group, which are located within signaling range, for examplearranged in a common room, to be associated with such a subgroup. Thosesubscriber terminals in a subscriber group which are connected to thesame switching center may also be combined to form such a subgroup.

[0032] A further embodiment of said development provides that after eachincoming call, at least one call number other than the at least onealready identified call number is in each case identified within such asubgroup in accordance with a predetermined sequence or a sequence whichis defined by a random principle. This means that the incoming call isnot always additionally signaled to a single subscriber terminal or tothe same subscriber terminals in a subgroup, but that other subscriberterminals are also used for the additional signaling of the incomingcall.

[0033] In conjunction with the subgroups which are formed within asubscriber group, at least one call number is expediently identified inthe table which defines that subscriber group. This identification isused for the purpose of carrying out additional signaling of the call tothe at least one other subscriber terminal in the case of an incomingcall which is directed to the subscriber terminal associated with theidentified call number. This procedure once again makes it easy toadminister the data records entered in this table.

[0034] A further refinement of the invention provides that the callnumber of the called subscriber terminal and/or of the callingsubscriber terminal is indicated on a display for the at least onesubscriber terminal to which an incoming call is additionally signaled.This means that the subscriber who accepts the incoming call on asubscriber terminal is informed of the subscriber terminal to which thecall was originally directed, and/or the subscriber terminal from whichthe call is coming. He can thus presume the intention of the callingsubscriber and react appropriately to this, if necessary.

[0035] According to a further embodiment of the invention, the entriesin said tables can be administered from one subscriber terminal. Thisallows each subscriber in a subscriber group to enter individual wishesin said tables. For example, each subscriber can define that subscribergroup or those subscriber groups to which he wishes to belong, and hecan also define those subscriber terminals to which a call which isdirected to his subscriber terminal should additionally be signaled, andthis is particularly advantageous when one subscriber has a number ofsubscriber terminals, which may be connected to different switchingcenters. For example, in a situation where the subscriber sometimesworks in the office and sometimes works at home, he can then include hissubscriber terminals which he has installed at home in a subscribergroup by entering their call numbers in said tables. Furthermore, attimes when he is traveling, he may also, if required, associate themobile terminal that he has with a subscriber group.

[0036] In order to provide protection against unauthorized access,administration of the entries may be allowed only after a subscriberauthorization process has been successfully carried out.

[0037] According to a further refinement of the invention, theassociation of a subscriber terminal with a subscriber group and/or withany subgroup which may exist is applicable only within a time intervalwhich can be set or within a recurrent time period. This allows thesubscriber to be relieved of regular administration of the entries insaid tables. For example, this provides for the subscriber to work athome on a specific day of the week. In this case, it is possible tospecify for this day of the week that the subscriber terminal which islocated in the subscriber's home area will be associated with a specificsubscriber group for his working area.

[0038] An exemplary embodiment of the invention will be explained inmore detail in the following text with reference to the drawing, inwhich:

[0039]FIG. 1 shows a first constellation of subscriber terminals andswitching centers within a telecommunications network in which themethod according to the invention can be used, and

[0040]FIG. 2 shows a second such constellation, which is suitable forthe method according to the invention, within a telecommunicationsnetwork.

[0041]FIG. 1 shows two switching centers VST 1 and VST 2, which areidentified by dashed lines. These symbolize switching centers within acommunications network. For example, the switching center VST 1 couldrepresent a telecommunications exchange within a landline network, andthe switching center VST 2 could represent a mobile switching centerwithin a mobile radio network. In the same way, the switching center VST2 could represent a switching node or a router within a packet switchingnetwork. Furthermore, the figure shows subscriber terminals Sub 1, Sub2, Sub 3 to Sub n, from and to which calls are passed from and to theswitching center VST 1. Said subscriber terminals are combined to form aso-called Centrex group, as is intended to be indicated by a cloudaround the subscriber terminals Sub 1 to Sub n. Incoming calls from andto the subscriber terminals Sub 1 c, Sub na to Sub nb indicated in thefigure are passed from and to the switching center VST 1 via theswitching center VST 2. Various tables GRT, RNT and CPT are shown withinthe switching center VST 1, and these are normally stored in a centraldatabase which is provided in the switching center but is notillustrated in the figure. The table GRT symbolizes a group table for asubscriber group, for example a call pick up group, in which the callnumbers CNo 1 to CNo n for the respective subscriber terminals Sub 1 toSub n are combined.

[0042] The table RNT represents a call number table, which is once againsubdivided into subtables RNT-Sub1 to RNT-Sub n. These subtables in eachcase contain those call numbers (for example the table RNT-Sub 1contains the call numbers CNo 1 a to CNo 1 m) to whose correspondingsubscriber terminals, for example Sub 1 c to Sub 1 m, a call which isdirected to the subscriber terminal Sub 1 is additionally intended to besignaled. By way of example, the call number CNo 1 a which is entered inthe subtable RNT-Sub 1 could be a call number for a subscriber terminalfor a subscriber who is at his workplace, and the call number CNo 1 mcould be the call number for a mobile terminal, within a mobile radionetwork, for the same subscriber. It is also feasible, for example, forthe call number CNo. 3 a to represent a call number or a network address(for example an IP address) for a subscriber who can be accessed via adata network (for example via the Internet) which is connected to theswitching center VST 1 and who is using, for example, so-called voiceover IP services.

[0043] All the calls which are directed to the subscriber terminalassociated with the pick up group are stored temporarily in the tableCPT, as is symbolized by Cd 1 to Cd m in the figure.

[0044] Furthermore, FIG. 1 shows a subscriber terminal Sub Ex which maybe connected to any switching center (not illustrated in the figure) inthe telecommunications network.

[0045] In FIG. 1, the steps which will be explained in the followingtext relating to the method according to the invention are identified bythe numbers 1-6.

[0046] In step 1, an external subscriber who is not part of the Centrexgroup uses his subscriber terminal Sub Ex to call a subscriber terminal,for example Sub 1, which is associated with a call pick up group, for aCentrex subscriber. A ringing tone then sounds on the subscriberterminal Sub 1, as is identified by “Ring” in the figure. In step 2, thecall number entries in the table GRT are used to check whether thesubscriber device Sub 1 is associated with a call pick up group. In thesituation where the subscriber terminal Sub 1 is associated with a callpick up group, the following steps are carried out:

[0047] In step 3, the call number of the calling subscriber is enteredin a transient table CPT which is used to temporarily store all thecalls that are waiting for that call pick up group, with the callnumbers of the calling subscriber terminals Cd 1 to Cd m based on theso-called FIFO principle (first in first out). In step 4, those callnumbers, for example CNo 1 a to CNo 1 m are looked for in the subtableRNT-Sub 1, which is provided for the subscriber terminal TN 1, in thecall number table RNT to whose subscriber terminals, for example Sub 1 cto Sub 1 m, the call which is directed to the subscriber terminal Sub 1is also intended to be signaled. Finally, in step 5, the connectionsetting-up request which is initiated by the external subscriber Sub Exis signaled not only to the subscriber terminal Sub 1 but also at thesame time and in parallel, or with a time delay, to the subscriberterminals Sub 1 c to Sub 1 m, corresponding to their call numbers asentered in the table RNT-Sub 1. This is indicated in the figure by“Ring” which symbolizes a ringing tone. The call, number of the calledsubscriber and/or the call number of the calling subscriber is alsoindicated on a display on each subscriber terminal to which the incomingcall is additionally intended to be signaled. When a call pick upsubscriber accepts the signaled call on a subscriber terminal, forexample Sub 1 m, that incoming call is connected to this subscriberterminal. At the same time, the additional call signaling to the othersubscriber terminals is stopped. In step 6, the call number of thesubscriber terminal Sub 1 to which the call was originally directed isremoved from the table CPT.

[0048] The elements illustrated in FIG. 2 differ from those illustratedin FIG. 1 only as explained in the following text:

[0049] Each of the call numbers CNo 1 to CNo n are followed by “P”markings in the table GRT. These call number markings define whichcalls, which are directed to the subscriber terminal corresponding tothe call number entered in the GRT, are additionally intended to besignaled to further subscriber terminals. Furthermore, a table OffRNT isshown, which is very similar to the call number table RNT in FIG. 1.This table is once again also subdivided into subtables Off A to Off Z.The subtables Off A to Off Z in each case contain call numbers, forexample CNo A1 to CNo An, whose subscriber terminals, for example Sub A1to Sub A2, are located in an area within which the calls which aresignaled to these subscriber terminals can be perceived audibly orvisually. Such an area within audible or visual signaling range isindicated in the figure by clouds, which are identified by dashed lines,for example around the subscriber terminals Sub A3 to Sub An and Sub Z1to Sub Z2. By way of example, the subscriber terminals with the callnumbers CNo A1 to CNo An may be located in an office area of a room,while the subscriber terminals with the call numbers CNo Z1 and CNo Z2may be installed in some other office area, which is physically separatefrom the first mentioned office area.

[0050] The method sequence according to the invention as shown in FIG. 2corresponds essentially as far as steps 1, 2, 3 and 6 are concerned tothe method steps which have already been explained in conjunction withFIG. 1. The table GRT in FIG. 2 shows, for example, that the call numberCNo 1 is identified by a “P”. This indicates that a call which isdirected to the subscriber terminal Sub 1 is additionally intended to besignaled to further subscriber terminals in the call pick up group.Accordingly, in step 4, a call number (for example the call numbers CNoA1, CNo B1, CNo C3 and CNo Z2), to whose subscriber terminals (forexample Sub A1, Sub B1, Sub C3 and Sub Z2) the call which is directed tothe subscriber terminal Sub 1 is additionally intended to be signaled islooked for among all the subtables Off A to Off Z which are included inthe table OffRNT and which each represent the subscriber terminalswithin an area within audible or signaling range. These call numbers mayin this case be looked for among said subtables by at least one callnumber in each case being identified by a marking in the respectivesubtables. A marking such as this may either be defined permanently fora single call number or for a number of specific call numbers, or may bemoved, after each incoming call has been successfully handled, from onecall number to another call number in the subtable, in a specificsequence or in a sequence defined by a random principle. In the figure,this “movement” of the marking is indicated by an arrow curved in acircular shape in the subtables Off A to Off Z. In the end, thisprocedure leads, in step 5, to an incoming call either always beingadditionally signaled to the same subscriber terminal, for example SubA3 within an area within audible or visual signaling range, for examplean office area, or always to a different subscriber terminal, on analternating basis.

[0051] The tables GRT, RNT and OffRNT as well as the subtables RNT-Sub 1to RNT-Sub n and Off A to Off Z may also be administered from onesubscriber terminal once one subscriber has been authorized as asubscriber group member (call pick up group) by means of an access code.This means that a subscriber terminal which is used by one subscribermay be associated with the corresponding subscriber group eithertemporarily or permanently. By way of example, he can include either histelephone at home or his mobile terminal, which is used in a mobileradio network, in the call pick up group for his working area in theoffice at certain times, so that he can audibly or visually perceivecalls to other subscriber terminals associated with that call pick upgroup and can then accept them and, conversely, his colleagues in theoffice can perceive and accept incoming calls which are directed to hissubscriber terminals.

[0052] It is likewise feasible for one or more subscriber terminals tobe associated with a call pick up group (instead of this being done bymanual administration) automatically as a function of a specific time,for example from 1400 to 1800 hrs, or periodically, for example only onMondays, so that incoming calls can also additionally be signaled tothese subscriber terminals.

1. A method for signaling an incoming call, which is directed to asubscriber terminal (Sub 1) which is associated with a subscriber group(Sub 1 to Sub n) and which a subscriber can also accept on any othersubscriber terminal associated with that subscriber group instead of onthe subscriber terminal being called, characterized in that the incomingcall is signaled not only to the called subscriber terminal (Sub 1) butalso to at least one subscriber terminal (Sub 1 c to Sub 1 m; Sub A3 toSub An) which is located beyond the signaling range of the calledsubscriber terminal.
 2. The method as claimed in claim 1, characterizedin that the additional signaling to the at least one subscriber terminalwhich is located beyond the signaling range of the called subscriberterminal is carried out in parallel or with a time delay for signalingthe incoming call to the called subscriber terminal.
 3. The method asclaimed in one of the preceding claims, characterized in that the atleast one subscriber terminal which is located beyond the signalingrange of the called subscriber terminal can be defined in advance forreceiving the additional signaling within the subscriber group.
 4. Themethod as claimed in one of the preceding claims, characterized in thatthose subscriber terminals (Sub A3 to Sub Z2) which are associated withthe subscriber group but are located beyond the signaling range of thecalled subscriber terminal are associated with subgroups within whichthe incoming call is additionally signaled to at least one subscriberterminal (Sub A3, Sub Z1) in the respective subgroup.
 5. The method asclaimed in claim 4, characterized in that the subscriber terminals whichare associated with such a subgroup are located within the signalingrange of the at least one subscriber terminal to which the incoming callis additionally signaled.
 6. The method as claimed in one of thepreceding claims, characterized in that one or more subscriber groupsare defined by the contents of a table (GRT) which is stored in aswitching center (VST 1) in a telecommunications network.
 7. The methodas claimed in claim 6, characterized in that a subscriber terminal isassociated with a subscriber group by entering its call number (CNo 1 toCNo n) in table fields which are provided for that subscriber groupwithin the table.
 8. The method as claimed in claim 6 or 7,characterized in that the at least one subscriber terminal to which theincoming call is additionally intended to be signaled is defined by thecontents of a further table (RNT; OffRNT), which is stored in theswitching center and is linked to the table (GRT) which defines thatsubscriber group.
 9. The method as claimed in claim 6 or 8,characterized in that the table (GRT) which defines the subscribergroup, and the further table (RNT; OffRNT) which is linked to it, arestored in a central database in the switching center (VST 1).
 10. Themethod as claimed in claim 8 or 9, characterized in that at least thecall number (CNo 1 c; CNo A3) of the at least one subscriber terminal(Sub 1 c; Sub A3) to which the incoming call is additionally intended tobe signaled is entered in said further table (RNT; OffRNT).
 11. Themethod as claimed in claim 10, characterized in that said subgroups(RNT-Sub1 to RNT-Sub n; Off A to Off Z) are formed by grouping callnumbers (CNo A1 to CNo An, . . . , CNo Z1 to CNo Z2), which are enteredin said further table (RNT; offRNT), of subscriber terminals, withinwhich subgroups (RNT-Sub1 to RNT-Sub n; Off A to Off Z) at least onecall number can in each case be identified as a special call number (CNoA1) to whose subscriber terminal the incoming call is additionallyintended to be signaled.
 12. The method as claimed in claim 11,characterized in that, after each incoming call, at least one callnumber other than the at least one already identified call number is ineach case identified within such a subgroup (RNT-Sub1 to RNT-Sub n; OffA to Off Z) in accordance with a predetermined sequence or a sequencewhich is defined by a random principle.
 13. The method as claimed inclaim 11, characterized in that, in the table (GRT) which defines thesubscriber group, at least one call number is identified for additionalsignaling of the incoming call which is directed to its subscriberterminal (Sub 1) to the at least one subscriber terminal which islocated beyond the signaling range.
 14. The method as claimed in one ofthe preceding claims, characterized in that the call number of thecalled subscriber terminal (Sub 1) and/or of the calling subscriberterminal (Sub Ex) is indicated on a display for the at least onesubscriber terminal to which an incoming call is additionally signaled.15. The method as claimed in one of the preceding claims, characterizedin that the entries in said tables can be administered from onesubscriber terminal.
 16. The method as claimed in claim 15,characterized in that the administration of the entries is allowed onlyafter a subscriber authorization process has been successfully carriedout.
 17. The method as claimed in one of the preceding claims,characterized in that the association of a subscriber terminal with asubscriber group and/or with any subgroup which may exist is applicableonly within a time interval which can be set or within a recurrent timeperiod.